Fluid regulator for supplying a consumer element with fluid from a fluid reservoir

ABSTRACT

A device or fluid regulator controls the supply of fluid to a consumer element from a fluid reservoir. A fluid supply line leads from the fluid reservoir to the consumer element. A valve is disposed in the fluid supply line. The valve element of the valve automatically opens the valve opening whenever downstream of the valve the consumer element has consumed a predetermined quantity of fluid. The valve is embodied as a capillary valve and downstream of the valve opening contains a capillary space that is connected to the fluid supply line, the capillary space being partially delimited by the valve element, which closes off the valve opening by the capillary force imparted by the fluid in the capillary space when the capillary space is filled with a predetermined amount of fluid.

BACKGROUND OF THE INVENTION

The present invention relates to a fluid regulator for supplying aconsumer element with fluid from a fluid reservoir and containing avalve for establishing communication between the fluid reservoir and theconsumer element when the consumer element has consumed a predeterminedquantity of fluid. The fluid consumer elements can, for example, be tipsor nibs for writing, painting, and brush devices or also application anddischarge elements of fluid dispensers.

With heretofore known writing instruments, such as fountain pens, thesupply of ink to the writing tips is effected by capillaries that bymeans of their capillary force draw ink out of a reservoir, whereby apressure relief opening in the reservoir is dimensioned such that onlyafter a partial vacuum drops below a certain value is the removed inkreplaced with air. In this connection, the partial vacuum in thereservoir suffices to prevent ink from running out despite its weight.These ink supply systems have the characteristic that when a temperaturechange of the ambient air occurs they are no longer discharge reliable,since the air in the reservoir expands and thus reduces the partialvacuum that prevents the discharge. Measures for preventing such adischarge of ink by means of additional capillary buffer storage meansfor the temporary accommodation of an excess volume of ink arecomplicated and expensive and are effective to only a limited extent.

EP 0 240 994 B1 discloses a device of the aforementioned general type,the valve of which is disposed between a fluid reservoir and anintermediate reservoir from which the consumer element is supplied withfluid via a capillary line. If the intermediate reservoir isincreasingly emptied as the fluid is consumed, there results at thatlocation a partial pressure so that the valve, one side of which bordersthe fluid reservoir and the other side of which borders the intermediatereservoir, opens and the intermediate reservoir is again filled withfluid. A characteristic of this system is that it can lead to permanentdisruption of the fluid supply if the partial vacuum is adjusted inanother manner.

It is an object of the present invention to provide a device of theaforementioned type that ensures a functionally reliable supply of aconsumer element with fluid with a simple construction.

SUMMARY OF THE INVENTION

This objective is realized in that the valve contains a capillary space,the capillary force of which displaces the valve element of the valveinto a position that closes the valve opening of the valve when thecapillary space fills itself entirely or partially with fluid from thefluid reservoir.

The inventive capillary regulator, the construction of which can beextraordinarily simple, operates in an extremely functionally reliablemanner due to the high forces that occur in capillary systems, andensures a high flow or discharge reliability of the consumer elementsupplied thereby.

Having the capillary space connected to the consumer element via a line,the capillarity of which is greater than that of the capillary space, orhaving the consumer element capillary, with its capillarity greater thanthat of the capillary space, ensure that the fluid supply line or theconsumer element, downstream of the capillary space, reliably,constantly, fully draw in fluid.

Pursuant to further advantageous features of the capillary valve, thecapillary space can on the whole be disc-shaped, whereby the valveopening is embodied in one end face and the other end face is formed bythe valve element. The valve element can have an elastic diaphragm,which can have a particularly high reliability if it is reinforced by areinforcing plate. The valve element could also have a ball for closingoff the valve opening.

The pressure acting from the fluid supply column can be used directly asthe valve opening force.

If the fluid reservoir is contained in a pouch, the dischargereliability is further increased since the venting of the interior ofthe elastic pouch is not necessary.

Pursuant to toward two advantageous examples of applications of theinventive device the consumer element can be the capillary writing tipof a drawing instrument, or the consumer element can be the printingunit of a printing device.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be explained by way of example and in furtherdetail subsequently with the aid of schematic drawings.

Illustrated are:

FIG. 1. a cross-sectional view through a felt-tipped pen equipped withthe inventive fluid regulator,

FIG. 2. an enlarged view of the capillary regulator contained in FIG. 1,

FIG. 3. a view of the valve element of the capillary regulator of FIG.2, and

FIG. 4 a schematic cross-sectional view of a printing device providedwith the inventive device,

FIG. 5 a detailed view of an embodiment modified from that shown in FIG.1.

DESCRIPTION OF PREFERRED EMBODIMENTS

Pursuant to FIG. 1, a felt-tipped pen has a casing 2, the interior ofwhich is subdivided into various chambers by partitions 4, 6, and 8. Thepartition 4 is provided with an annular flange 10 upon which is placed aflexible or elastic bag or pouch 12 that contains a fluid or liquidreservoir 14, whereby the fluid can be any known writing fluid, such asink. An opening or aperture 16 leads through the partition 4 into a line18, from which a valve opening 20 leads through the partition 6. Restingagainst that end face of the valve opening 20 that is remote from theline 18 is a valve element 22, whereby the distance "d" between thevalve element 22 and the partition 6 has capillary dimensions as will beexplained subsequently.

The line 18 can be filled with material that dampens the throughflow sothat pressure waves from the fluid reservoir 14 have no effect upon thevalve functions.

Pursuant to FIG. 1, formed below the valve opening 20 in the partition 6is a line 24, the diameter of which is advantageously less than thedistance "d" and that opens via a connecting opening 26 into the spacebetween the partition 6 and the valve element 22. The line 24 leads to acapillary writing tip or nib 28 that is of conventional construction andis of a type used for felt-tip pens. The writing tip 28 is disposed in aflange of the partition 8, with the forward region of the tipadditionally being held by a conically extending part of the casing 2.

The writing tip 28 can also project directly into the space between thevalve element 22 and the partition 6.

Pressure relief openings 30, 32, and 34 take care of venting theinterior of the casing 2.

The overall plate-like valve element 22, which between itself and thepartition 6 delimits a plate or disk-shaped capillary space 36 having athickness "d", is pivotably connected with the partition 4 as indicatedat the reference numeral 38 and projects into a recess 40 of thepartition 8 that forms an opening delimitation for the valve element 22.Instead of a pivotable connection, an elastic connection can also beprovided.

Prior to explaining the function of the described device, severalphysical principles are briefly noted:

With the valve element 22 that closes off the valve opening 20, via thevalve opening 20 and via the fluid column that is present on the leftside of the valve opening 20, the following force acts upon the valveelement 22:

    K=π×r.sup.2 ×h×a

whereby

r: radius of the valve opening

h: height of the fluid column

a: specific weight of the fluid

If the valve element 22, on that side facing the capillary space 36, andthe partition 6, on that side facing the capillary space 36, are made ofa material that is wetted by the fluid, the fluid will be drawn into thecapillary space 36 as a consequence of the capillary attraction andunder circumstances additionally due to the hydrostatic pressure of thefluid column, will be pressed into the capillary space 36. Due to thefluid in the capillary space, this leads to the valve element 22 beingdrawn in a closing direction, i.e. in abutment against the edge of thevalve opening 20, with the following force:

    K.sub.s =2×o×f/d

whereby

o: surface tension of the fluid,

d: thickness of the capillary space 36, and

f: surface of the valve element 22 wetted by fluid.

Usual dimensions are in the following ranges:

d: 0.01 to 1 mm

f: 1 mm² to several cm²

h: 1 cm to 1 m

r: 0.01 to 5 mm

o: 10 to 70×10⁻² N/m

With d: 0.1 mm, o=50×10⁻² N/m, f=1 cm², there results: K₂ =0.1N.

With r=0.2 mm, h=5 cm, a=10⁴ N/m³ there results: K=6×10⁻⁵ N.

Thus, the opening force exerted by the height of the fluid columnamounts to only a fraction of the closing force, as a consequence ofwhich the valve is closed extremely reliably and when impact movementsoccur there is no danger of opening as long as the mass of the valveelement 22 is small.

The function of the described felt-tip pen is as follows:

It is assumed that the felt-tip pen is in the state shown in FIG. 1,i.e., the valve element 22 closes the valve opening 20, since thecapillary space 36 is adequately filled with fluid. If the felt-tip penis now used to write and fluid is delivered from the writing tip 28 thecapillary space 36 is increasingly emptied. The closing force of thevalve element 22 thereby decreases, so that when the capillary space issufficiently emptied, the fluid pressure and/or a shaking movement opensthe valve element 22, whereupon the capillary space again fills withfluid due to the hydrostatic pressure and also the capillarity, and thevalve element 22 again closes the opening 20. The process begins anew.It is advantageous for the line 24 to have a greater capillarity thandoes the capillary space 36, since this ensures that the line 24 "sucks"the capillary space "empty".

It is to be understood that the described device can be modified in anumber of ways. The way the interior of the casing is subdivided canvary; the writing tip can be different; the arrangement of the ventingopenings can be modified; in the region of the pouch 12 the casing canbe adapted to be opened so that the pouch can easily be replaced. Evenif the entire device has been completely used up, it is automaticallyreliably completely filled with ink after a new pouch is installedwithout there being any danger of contamination or clogging.

FIGS. 2 and 3 show a modified construction of a valve. In thisembodiment the valve element 22 is an elastic membrane or diaphragm 50that is reinforced by a reinforcing plate 52. In its upper region 54,the elastic diaphragm 50 is rigidly connected with the partition 6, sothat between the region 54, which is rigidly connected, for example, bygluing, and the region reinforced by the reinforcing plate 52, a regionremains that forms a flexible joint of the valve element 22. Thecapillary space 36 is defined by an appropriately deep recess in thepartition 6, whereby that end face of the valve opening 20 that facesthe valve element 22 projects by the thickness or depth of the capillaryspace. With this construction of the valve element 22, a particularlyhigh functional reliability is achieved with a simple construction.

FIG. 4 shows the construction of FIG. 1 and FIG. 2 schematically in itsuse with a printing unit 56 of a printing device 58, for example as usedin ink jet printers. Here the fluid reservoir 14 directly borders on thepartition 6 with the valve opening 20. The writing tip 28 (FIG. 1)corresponds to a capillary wick 60 that supplies the printing unit 56with fluid.

FIG. 5 shows an embodiment of the inventive regulator that is modifiedrelative to the embodiment of FIG. 1: the valve element 22 is hereembodied as a plate 70 that is pivotably mounted on the partition 6 andhas an opening in which a ball 72 is secured. The ball 72 can also bemonolithically formed with the plate 70, for example by injectionmolding. By means of the ball 72, which should be made of as light amaterial as possible, the closing reliability of the valve 20,22 isimproved and its sensitivity to contamination is reduced. A furtherdifference from the embodiment of FIG. 1 is that the consumer element,which is here also embodied as a capillary writing tip 28, directlyborders on the capillary space 36, which simplifies construction andincreases the functional reliability, especially since the capillarityof the writing tip 28 is greater than that of the capillary space 36. Inother respects, the function is the same as described in conjunctionwith the embodiment of FIG. 1.

The present invention is, of course, in no way restricted to thespecific disclosure of the specification and drawings, but alsoencompasses any modifications within the scope of the appended claims.

What is claimed is:
 1. A fluid regulator for supplying a consumerelement with fluid from a fluid reservoir, comprising:a valve 20, 22 forestablishing communication between said fluid reservoir 14 and saidconsumer element 28; 60, 56 when said consumer element has consumed apredetermined quantity of fluid, wherein said valve contains a capillaryspace 36, a capillary force of which displaces a valve element 22 ofsaid valve into a position that closes off a valve opening 20 of saidvalve when said capillary space 36 fills itself at least partially withfluid from said fluid reservoir
 14. 2. A fluid regulator according toclaim 1, which includes a line 24 that connects said capillary space 36to said consumer element 28; 60, 56, wherein the capillarity of saidline 24 is greater than that of said capillary space
 36. 3. A fluidregulator according to claim 1, wherein said consumer element 28; 60, 56is capillary and has a capillarity that is greater than that of saidcapillary space
 36. 4. A fluid regulator according to claim 1, whereinsaid capillary space is substantially disc-shaped, with said valveopening defined in one end face thereof and a second end face defined bysaid valve element.
 5. A fluid regulator according to claim 1, whereinsaid valve element 22 is provided with an elastic diaphragm
 50. 6. Afluid regulator according to claim 5, which includes a reinforcing plate52 for reinforcing said elastic diaphragm
 50. 7. A fluid regulatoraccording to claim 1, wherein said valve element 22 is provided with aball 72 for closing off said valve opening
 20. 8. A fluid regulatoraccording to claim 1, which includes means for closing said valveagainst the pressure of a fluid column that acts from said fluidreservoir 14 upon said valve opening
 20. 9. A fluid regulator accordingto claim 1, which includes a pouch 12 in which is contained said fluidreservoir
 14. 10. A fluid regulator according to claim 1, wherein saidconsumer element is a capillary writing tip 28 of a drawing instrument.11. A fluid regulator according to claim 1, wherein said consumerelement is a printing unit 56 of a printing device
 58. 12. A fluidregulator for supplying a consumer element with fluid from a fluidreservoir, comprisinga valve for establishing communication between saidfluid reservoir and said consumer element when said consumer element hasconsumed a predetermined quantity of fluid, said valve comprising avalve element for opening and closing a valve opening between said fluidreservoir and said consumer element and further comprising a capillaryspace on a downstream side of said valve opening, said capillary spacebeing in direct communication with the outer atmosphere and in fluidconnection with said consumer element and being at least partiallydefined by said valve element as to apply a capillary force onto saidvalve element depending on the volume of fluid within said capillaryspace, so that said valve closes, when said capillary space fills itselfat least partially with fluid from said fluid reservoir.